Subsea Control Modules (SCMs) are commonly used to provide well control functions during the production phase of subsea oil and gas production. Typical well control functions and monitoring provided by the SCM are as follows: 1) Actuation of fail-safe return production tree actuators and downhole safety valves; 2) Actuation of flow control choke valves, shut-off valves, etc.; 3) Actuation of manifold diverter valves, shut-off valves, etc.; 4) Actuation of chemical injection valves; 5) Actuation and monitoring of Surface Controlled Reservoir Analysis and Monitoring Systems (SCRAMS) sliding sleeve, choke valves; 6) Monitoring of downhole pressure, temperature and flowrates; 7) Monitoring of sand probes, production tree and manifold pressures, temperatures, and choke positions.
The close proximity of the typical SCM to the subsea production tree, coupled with its electro-hydraulic design allows for quick response times of tree valve actuations. The typical SCM receives electrical power, communication signals and hydraulic power supplies from surface control equipment. The subsea control module and production tree are generally located in a remote location relative to the surface control equipment. Redundant supplies of communication signals, electrical, and hydraulic power are transmitted through umbilical hoses and cables ranging from one thousand feet to several miles in length, linking surface equipment to subsea equipment. Electronics equipment located inside the SCM conditions electrical power, processes communications signals, transmits status and distributes power to solenoid piloting valves, pressure transducers and temperature transducers.
Low flowrate solenoid piloting valves are typically used to pilot high flowrate control valves. These control valves transmit hydraulic power to end devices such as subsea production tree valve actuators, choke valves and downhole safety valves. The status condition of control valves and their end devices are read by pressure transducers located on the output circuit of the control valves. Auxiliary equipment inside the typical SCM consists of hydraulic accumulators for hydraulic power storage, hydraulic filters for the reduction of fluid particulates, electronics vessels, and a pressure/temperature compensation system.
Previous devices have used an oil-filled chamber to compensate for hydrostatic pressure increase outside of the device during use to keep seawater away from cable assemblies. An SCM is typically provided with a latching mechanism that extends through the body of the SCM and that has retractable and extendable dogs or cams thereon to engage a mating receptacle in a base plate.